1. Field of the Invention
The present invention relates to a method of manufacturing a nozzle plate for a liquid ejecting head such as an inkjet head.
2. Description of Related Art
An ejection surface of a nozzle plate having thereon nozzles for ejecting droplets are sometimes provided with a water-repellent film. This water-repellent film is for restraining variation in an amount of a droplet ejected, and for restraining a flight direction of the droplet from curving. Japanese Unexamined Patent Publication No. 355957/2002 (Tokukai 2002-355957) discloses an inkjet head having an orifice plate serving as a nozzle plate whose ejection surface has thereon a first ink-repellent film and a second ink-repellent film thicker than the first-ink repellent film. The first ink-repellent film is formed closer to a nozzle opening than the second ink-repellent film is to the same. That is, two ink-repellent films respectively having different thicknesses are formed so as to create different levels around the nozzle opening. The first ink-repellent film exhibits higher ink-repellency than the second ink-repellent film. Therefore, ink adhered to the first ink-repellent film is attracted to the second ink-repellent film, thus enabling stable ejection of any type of ink.
The above mentioned Tokukai 2002-355957 describes the two types of ink-repellent films that are formed as follows. First, a photoresist is patterned on the ejection surface of the orifice plate so as to form a pattern of the second ink-repellent film. In this step, the photoresist is applied throughout the entire ejection surface. The photoresist is then exposed, using a photomask having the pattern of the second ink-repellent film, and is subjected to development thereafter. Next, the first ink-repellent film is formed on a part of the orifice plate without the photoresist, using the pattern of the photoresist as a mask. After the photoresist is removed, the second ink-repellent film is formed. Since the first ink-repellent film is a nonconductor, the second ink-repellent film is not formed on the first ink repellent film. Finally, oxygen plasma is applied to the back surface of the ejection surface to remove the first ink-repellent film, made of an organic material, except on the ejection surface.
The above method requires that a photomask having a pattern be manufactured beforehand to form the two different types of ink-repellent films respectively having different thicknesses on a nozzle plate. However, manufacturing of a photomask takes a lot of work and time, and thus contributes to an increase in the production cost of the nozzle plate. Further, when manufacturing a plurality of types of nozzle plates whose respective positions of different levels formed around their ejection openings are different, photomasks for each type of the nozzle plate must be manufactured. Thus, the above method is not suitable for manufacturing a plurality of types of nozzle plates.